U.S. District Judge Daniel Hovland, who is based in Bismarck, cited the 1973 Roe v. Wade decision by the U.S. Supreme Court, saying "no state may deprive a woman of the choice to terminate her pregnancy at a point prior to viability."

"The controversy over a woman's right to choose to have an abortion will never end. The issue is undoubtedly one of the most divisive of social issues. The United States Supreme Court will eventually weigh in on this emotionally-fraught issue but, until that occurs, this Court is obligated to uphold existing Supreme Court precedent," Hovland said.

In July, Hovland had temporarily blocked the ban from taking effect.

The Associated Press writes:

"North Dakota's heartbeat measure was among four anti-abortion bills that Republican Gov. Jack Dalrymple signed into law last year with overwhelming support from the state's Republican-led Legislature. Backed by the New York-based Center for Reproductive Rights, the state's only abortion clinic, the Red River Clinic in Fargo, filed a lawsuit against the heartbeat law last July."

The North Dakota attorney general's office had no immediate comment on the ruling, a spokeswoman said, according to Reuters.

The Supreme Court recently declined to hear an appeal of a ruling that struck down a 20-week abortion ban in Arizona.

And in Arkansas, a law banning most abortions after 12 weeks was struck down last month by another federal judge citing similar grounds. Reuters says the Arkansas attorney general is appealing that ruling.